1. Field of the Invention
This invention relates to a distance detecting device in a photographing apparatus such as a movie camera, a still camera or a TV camera, and more particularly to a distance detecting device in a camera which adopts the distance measuring principle of the base line type range finder to electrically detect the relative positional relation between two images to thereby enable the distance from the camera to an object to be known.
2. Description of the Prior Art
A variety of electrical two-image relative position detecting type distance detecting devices have heretofore been proposed. As a typical example thereof, U.S. Pat. No. 4,004,852 discloses a distance detecting device in which two detection images of an object formed with an imaged position deviation corresponding to the distance to the target object by a pair of fixedly disposed imaging optical systems are received by a pair of or one photosensor array device and at this time, binary-form-transformed picture element signal rows from individual photosensors for one image are successively shifted relative to binary-form-transformed picture element signal rows from individual photosensors for the other image and, in the process of the relative shift of the binary-form-transformed picture element signal rows, the coincidence or incoincidence of each binary-form-transformed picture element signal row with the two images is detected, and the amount of relative shift of the binary-form-transformed picture element signal rows from the start of the shift until the binary-form-transformed picture element signal rows can be regarded as being substantially coincident with the images, whereby this amount of shift of the binary-form-transformed picture element signal rows is used as the information of the distance to the target object.
The distance detecting device of this type can provide an automatic focus adjusting system of high performance by being incorporated into a camera while, on the other hand, it suffers from the following problems due to the construction thereof. That is, in the device of this type, two optical systems for constituting a picture-taking optical system and a range-finding optical system are entirely independent of each other and therefore, the optical axis of one optical system for imaging the view field which provides the standard for distance detection and the optical axis of the picture-taking optical system must unavoidably be disposed with some distance therebetween and therefore, it is very difficult to make the picture-taking field of the picture-taking optical system and the standard field of the distance detecting device exactly coincident with each other, and thus there is parallax which is generally questionable as a disadvantage of such distance detecting device.
Also, where such distance detecting device is applied to a photographing apparatus such as a camera, a range-finding optical system comprising two optical systems must be installed around the picture-taking optical system and this leads to a great volume and heavy weight of the apparatus which are great limitations in the design of the photographing apparatus. Furthermore, where two images are to be formed in a predetermined positional relationship on the surface of a pair of or one photosensor array device, much effort must be made to adjust the range-finding optical system, and this makes the operation for adjustment very cumbersome and the photographing apparatus expensive.